package com.feixc.xsimple.eventx;

import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 有序链接阻塞队列
 * 
 * @author xuzhigang01
 */
public class SortedBlockingQueue<E> extends LinkedBlockingQueue<E> {
	private static final long serialVersionUID = -7694436200165367406L;

	static class Node<E> {
		E item;
		Node<E> next;

		Node(E x) {
			item = x;
		}
	}

	private final int capacity;

	/** Current number of elements */
	private final AtomicInteger count = new AtomicInteger(0);

	/**
	 * Head of linked list. Invariant: head.item == null
	 */
	private transient Node<E> head;

	/**
	 * Tail of linked list. Invariant: last.next == null
	 */
	private transient Node<E> last;

	/** Lock held by take, poll, etc */
	private final ReentrantLock takeLock = new ReentrantLock();

	/** Wait queue for waiting takes */
	private final Condition notEmpty = takeLock.newCondition();

	/** Lock held by put, offer, etc */
	private final ReentrantLock putLock = new ReentrantLock();

	/** Wait queue for waiting puts */
	private final Condition notFull = putLock.newCondition();

	/**
	 * Signals a waiting take. Called only from put/offer (which do not
	 * otherwise ordinarily lock takeLock.)
	 */
	private void signalNotEmpty() {
		final ReentrantLock takeLock = this.takeLock;
		takeLock.lock();
		try {
			notEmpty.signal();
		} finally {
			takeLock.unlock();
		}
	}

	/**
	 * Signals a waiting put. Called only from take/poll.
	 */
	private void signalNotFull() {
		final ReentrantLock putLock = this.putLock;
		putLock.lock();
		try {
			notFull.signal();
		} finally {
			putLock.unlock();
		}
	}

	/**
	 * insert node to queue.
	 *
	 * @param node
	 *            the node
	 */
	@SuppressWarnings("unchecked")
	private void enqueue(Node<E> node) {
		// assert putLock.isHeldByCurrentThread();
		// assert last.next == null;
		/* last = last.next = node; */

		Node<E> prev = head;
		Node<E> curr = head.next;
		while (curr != null) {
			if (((Comparable<E>)node.item).compareTo((E)curr.item) < 0) {
				prev.next = node;
				node.next = curr;
				break;
			}
			prev = curr;
			curr = curr.next;
		}
		if (node.next == null) {
			last = last.next = node;
		}
	}

	/**
	 * Removes a node from head of queue.
	 *
	 * @return the node
	 */
	private E dequeue() {
		// assert takeLock.isHeldByCurrentThread();
		// assert head.item == null;
		Node<E> h = head;
		Node<E> first = h.next;
		h.next = h; // help GC
		head = first;
		E x = first.item;
		first.item = null;
		return x;
	}

	/**
	 * Lock to prevent both puts and takes.
	 */
	private void lockAll() {
		putLock.lock();
		takeLock.lock();
	}

	/**
	 * Unlock to allow both puts and takes.
	 */
	private void unlockAll() {
		takeLock.unlock();
		putLock.unlock();
	}

	// /**
	// * Tells whether both locks are held by current thread.
	// */
	// boolean isFullyLocked() {
	// return (putLock.isHeldByCurrentThread() &&
	// takeLock.isHeldByCurrentThread());
	// }

	/**
	 * Creates a {@code LinkedBlockingQueue} with a capacity of
	 * {@link Integer#MAX_VALUE}.
	 */
	public SortedBlockingQueue() {
		this(Integer.MAX_VALUE);
	}

	/**
	 * Creates a {@code LinkedBlockingQueue} with the given (fixed) capacity.
	 *
	 * @param capacity
	 *            the capacity of this queue
	 * @throws IllegalArgumentException
	 *             if {@code capacity} is not greater than zero
	 */
	public SortedBlockingQueue(int capacity) {
		if (capacity <= 0)
			throw new IllegalArgumentException();
		this.capacity = capacity;
		last = head = new Node<E>(null);
	}

	/**
	 * Creates a {@code LinkedBlockingQueue} with a capacity of
	 * {@link Integer#MAX_VALUE}, initially containing the elements of the given
	 * collection, added in traversal order of the collection's iterator.
	 *
	 * @param c
	 *            the collection of elements to initially contain
	 * @throws NullPointerException
	 *             if the specified collection or any of its elements are null
	 */
	public SortedBlockingQueue(Collection<? extends E> c) {
		this(Integer.MAX_VALUE);
		final ReentrantLock putLock = this.putLock;
		putLock.lock(); // Never contended, but necessary for visibility
		try {
			int n = 0;
			for (E e : c) {
				if (e == null)
					throw new NullPointerException();
				if (n == capacity)
					throw new IllegalStateException("Queue full");
				enqueue(new Node<E>(e));
				++n;
			}
			count.set(n);
		} finally {
			putLock.unlock();
		}
	}

	// this doc comment is overridden to remove the reference to collections
	// greater in size than Integer.MAX_VALUE
	/**
	 * Returns the number of elements in this queue.
	 *
	 * @return the number of elements in this queue
	 */
	public int size() {
		return count.get();
	}

	// this doc comment is a modified copy of the inherited doc comment,
	// without the reference to unlimited queues.
	/**
	 * Returns the number of additional elements that this queue can ideally (in
	 * the absence of memory or resource constraints) accept without blocking.
	 * This is always equal to the initial capacity of this queue less the
	 * current {@code size} of this queue.
	 *
	 * <p>
	 * Note that you <em>cannot</em> always tell if an attempt to insert an
	 * element will succeed by inspecting {@code remainingCapacity} because it
	 * may be the case that another thread is about to insert or remove an
	 * element.
	 */
	public int remainingCapacity() {
		return capacity - count.get();
	}

	/**
	 * Inserts the specified element at the tail of this queue, waiting if
	 * necessary for space to become available.
	 *
	 * @throws InterruptedException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 */
	public void put(E e) throws InterruptedException {
		if (e == null)
			throw new NullPointerException();
		// Note: convention in all put/take/etc is to preset local var
		// holding count negative to indicate failure unless set.
		int c = -1;
		Node<E> node = new Node<E>(e);
		final ReentrantLock putLock = this.putLock;
		final AtomicInteger count = this.count;
		putLock.lockInterruptibly();
		try {
			/*
			 * Note that count is used in wait guard even though it is not
			 * protected by lock. This works because count can only decrease at
			 * this point (all other puts are shut out by lock), and we (or some
			 * other waiting put) are signalled if it ever changes from
			 * capacity. Similarly for all other uses of count in other wait
			 * guards.
			 */
			while (count.get() == capacity) {
				notFull.await();
			}
			enqueue(node);
			c = count.getAndIncrement();
			if (c + 1 < capacity)
				notFull.signal();
		} finally {
			putLock.unlock();
		}
		if (c == 0)
			signalNotEmpty();
	}

	/**
	 * Inserts the specified element at the tail of this queue, waiting if
	 * necessary up to the specified wait time for space to become available.
	 *
	 * @return {@code true} if successful, or {@code false} if the specified
	 *         waiting time elapses before space is available.
	 * @throws InterruptedException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 */
	public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException {

		if (e == null)
			throw new NullPointerException();
		long nanos = unit.toNanos(timeout);
		int c = -1;
		final ReentrantLock putLock = this.putLock;
		final AtomicInteger count = this.count;
		putLock.lockInterruptibly();
		try {
			while (count.get() == capacity) {
				if (nanos <= 0)
					return false;
				nanos = notFull.awaitNanos(nanos);
			}
			enqueue(new Node<E>(e));
			c = count.getAndIncrement();
			if (c + 1 < capacity)
				notFull.signal();
		} finally {
			putLock.unlock();
		}
		if (c == 0)
			signalNotEmpty();
		return true;
	}

	/**
	 * Inserts the specified element at the tail of this queue if it is possible
	 * to do so immediately without exceeding the queue's capacity, returning
	 * {@code true} upon success and {@code false} if this queue is full. When
	 * using a capacity-restricted queue, this method is generally preferable to
	 * method {@link BlockingQueue#add add}, which can fail to insert an element
	 * only by throwing an exception.
	 *
	 * @throws NullPointerException
	 *             if the specified element is null
	 */
	public boolean offer(E e) {
		if (e == null)
			throw new NullPointerException();
		final AtomicInteger count = this.count;
		if (count.get() == capacity)
			return false;
		int c = -1;
		Node<E> node = new Node<E>(e);
		final ReentrantLock putLock = this.putLock;
		putLock.lock();
		try {
			if (count.get() < capacity) {
				enqueue(node);
				c = count.getAndIncrement();
				if (c + 1 < capacity)
					notFull.signal();
			}
		} finally {
			putLock.unlock();
		}
		if (c == 0)
			signalNotEmpty();
		return c >= 0;
	}

	public E take() throws InterruptedException {
		E x;
		int c = -1;
		final AtomicInteger count = this.count;
		final ReentrantLock takeLock = this.takeLock;
		takeLock.lockInterruptibly();
		try {
			while (count.get() == 0) {
				notEmpty.await();
			}
			x = dequeue();
			c = count.getAndDecrement();
			if (c > 1)
				notEmpty.signal();
		} finally {
			takeLock.unlock();
		}
		if (c == capacity)
			signalNotFull();
		return x;
	}

	public E poll(long timeout, TimeUnit unit) throws InterruptedException {
		E x = null;
		int c = -1;
		long nanos = unit.toNanos(timeout);
		final AtomicInteger count = this.count;
		final ReentrantLock takeLock = this.takeLock;
		takeLock.lockInterruptibly();
		try {
			while (count.get() == 0) {
				if (nanos <= 0)
					return null;
				nanos = notEmpty.awaitNanos(nanos);
			}
			x = dequeue();
			c = count.getAndDecrement();
			if (c > 1)
				notEmpty.signal();
		} finally {
			takeLock.unlock();
		}
		if (c == capacity)
			signalNotFull();
		return x;
	}

	public E poll() {
		final AtomicInteger count = this.count;
		if (count.get() == 0)
			return null;
		E x = null;
		int c = -1;
		final ReentrantLock takeLock = this.takeLock;
		takeLock.lock();
		try {
			if (count.get() > 0) {
				x = dequeue();
				c = count.getAndDecrement();
				if (c > 1)
					notEmpty.signal();
			}
		} finally {
			takeLock.unlock();
		}
		if (c == capacity)
			signalNotFull();
		return x;
	}

	public E peek() {
		if (count.get() == 0)
			return null;
		final ReentrantLock takeLock = this.takeLock;
		takeLock.lock();
		try {
			Node<E> first = head.next;
			if (first == null)
				return null;
			else
				return first.item;
		} finally {
			takeLock.unlock();
		}
	}

	/**
	 * Unlinks interior Node p with predecessor trail.
	 */
	void unlink(Node<E> p, Node<E> trail) {
		// assert isFullyLocked();
		// p.next is not changed, to allow iterators that are
		// traversing p to maintain their weak-consistency guarantee.
		p.item = null;
		trail.next = p.next;
		if (last == p)
			last = trail;
		if (count.getAndDecrement() == capacity)
			notFull.signal();
	}

	/**
	 * Removes a single instance of the specified element from this queue, if it
	 * is present. More formally, removes an element {@code e} such that
	 * {@code o.equals(e)}, if this queue contains one or more such elements.
	 * Returns {@code true} if this queue contained the specified element (or
	 * equivalently, if this queue changed as a result of the call).
	 *
	 * @param o
	 *            element to be removed from this queue, if present
	 * @return {@code true} if this queue changed as a result of the call
	 */
	public boolean remove(Object o) {
		if (o == null)
			return false;
		lockAll();
		try {
			for (Node<E> trail = head, p = trail.next; p != null; trail = p, p = p.next) {
				if (o.equals(p.item)) {
					unlink(p, trail);
					return true;
				}
			}
			return false;
		} finally {
			unlockAll();
		}
	}

	/**
	 * Returns {@code true} if this queue contains the specified element. More
	 * formally, returns {@code true} if and only if this queue contains at
	 * least one element {@code e} such that {@code o.equals(e)}.
	 *
	 * @param o
	 *            object to be checked for containment in this queue
	 * @return {@code true} if this queue contains the specified element
	 */
	public boolean contains(Object o) {
		if (o == null)
			return false;
		lockAll();
		try {
			for (Node<E> p = head.next; p != null; p = p.next)
				if (o.equals(p.item))
					return true;
			return false;
		} finally {
			unlockAll();
		}
	}

	/**
	 * Returns an array containing all of the elements in this queue, in proper
	 * sequence.
	 *
	 * <p>
	 * The returned array will be "safe" in that no references to it are
	 * maintained by this queue. (In other words, this method must allocate a
	 * new array). The caller is thus free to modify the returned array.
	 *
	 * <p>
	 * This method acts as bridge between array-based and collection-based APIs.
	 *
	 * @return an array containing all of the elements in this queue
	 */
	public Object[] toArray() {
		lockAll();
		try {
			int size = count.get();
			Object[] a = new Object[size];
			int k = 0;
			for (Node<E> p = head.next; p != null; p = p.next)
				a[k++] = p.item;
			return a;
		} finally {
			unlockAll();
		}
	}

	/**
	 * Returns an array containing all of the elements in this queue, in proper
	 * sequence; the runtime type of the returned array is that of the specified
	 * array. If the queue fits in the specified array, it is returned therein.
	 * Otherwise, a new array is allocated with the runtime type of the
	 * specified array and the size of this queue.
	 *
	 * <p>
	 * If this queue fits in the specified array with room to spare (i.e., the
	 * array has more elements than this queue), the element in the array
	 * immediately following the end of the queue is set to {@code null}.
	 *
	 * <p>
	 * Like the {@link #toArray()} method, this method acts as bridge between
	 * array-based and collection-based APIs. Further, this method allows
	 * precise control over the runtime type of the output array, and may, under
	 * certain circumstances, be used to save allocation costs.
	 *
	 * <p>
	 * Suppose {@code x} is a queue known to contain only strings. The following
	 * code can be used to dump the queue into a newly allocated array of
	 * {@code String}:
	 *
	 * <pre>
	 * String[] y = x.toArray(new String[0]);
	 * </pre>
	 *
	 * Note that {@code toArray(new Object[0])} is identical in function to
	 * {@code toArray()}.
	 *
	 * @param a
	 *            the array into which the elements of the queue are to be
	 *            stored, if it is big enough; otherwise, a new array of the
	 *            same runtime type is allocated for this purpose
	 * @return an array containing all of the elements in this queue
	 * @throws ArrayStoreException
	 *             if the runtime type of the specified array is not a supertype
	 *             of the runtime type of every element in this queue
	 * @throws NullPointerException
	 *             if the specified array is null
	 */
	@SuppressWarnings("unchecked")
	public <T> T[] toArray(T[] a) {
		lockAll();
		try {
			int size = count.get();
			if (a.length < size)
				a = (T[]) java.lang.reflect.Array.newInstance(a.getClass().getComponentType(), size);

			int k = 0;
			for (Node<E> p = head.next; p != null; p = p.next)
				a[k++] = (T) p.item;
			if (a.length > k)
				a[k] = null;
			return a;
		} finally {
			unlockAll();
		}
	}

	public String toString() {
		lockAll();
		try {
			Node<E> p = head.next;
			if (p == null)
				return "[]";

			StringBuilder sb = new StringBuilder();
			sb.append('[');
			for (;;) {
				E e = p.item;
				sb.append(e == this ? "(this Collection)" : e);
				p = p.next;
				if (p == null)
					return sb.append(']').toString();
				sb.append(',').append(' ');
			}
		} finally {
			unlockAll();
		}
	}

	/**
	 * Atomically removes all of the elements from this queue. The queue will be
	 * empty after this call returns.
	 */
	public void clear() {
		lockAll();
		try {
			for (Node<E> p, h = head; (p = h.next) != null; h = p) {
				h.next = h;
				p.item = null;
			}
			head = last;
			// assert head.item == null && head.next == null;
			if (count.getAndSet(0) == capacity)
				notFull.signal();
		} finally {
			unlockAll();
		}
	}

	/**
	 * @throws UnsupportedOperationException
	 *             {@inheritDoc}
	 * @throws ClassCastException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 * @throws IllegalArgumentException
	 *             {@inheritDoc}
	 */
	public int drainTo(Collection<? super E> c) {
		return drainTo(c, Integer.MAX_VALUE);
	}

	/**
	 * @throws UnsupportedOperationException
	 *             {@inheritDoc}
	 * @throws ClassCastException
	 *             {@inheritDoc}
	 * @throws NullPointerException
	 *             {@inheritDoc}
	 * @throws IllegalArgumentException
	 *             {@inheritDoc}
	 */
	public int drainTo(Collection<? super E> c, int maxElements) {
		if (c == null)
			throw new NullPointerException();
		if (c == this)
			throw new IllegalArgumentException();
		boolean signalNotFull = false;
		final ReentrantLock takeLock = this.takeLock;
		takeLock.lock();
		try {
			int n = Math.min(maxElements, count.get());
			// count.get provides visibility to first n Nodes
			Node<E> h = head;
			int i = 0;
			try {
				while (i < n) {
					Node<E> p = h.next;
					c.add(p.item);
					p.item = null;
					h.next = h;
					h = p;
					++i;
				}
				return n;
			} finally {
				// Restore invariants even if c.add() threw
				if (i > 0) {
					// assert h.item == null;
					head = h;
					signalNotFull = (count.getAndAdd(-i) == capacity);
				}
			}
		} finally {
			takeLock.unlock();
			if (signalNotFull)
				signalNotFull();
		}
	}

	/**
	 * Returns an iterator over the elements in this queue in proper sequence.
	 * The elements will be returned in order from first (head) to last (tail).
	 *
	 * <p>
	 * The returned iterator is a "weakly consistent" iterator that will never
	 * throw {@link java.util.ConcurrentModificationException
	 * ConcurrentModificationException}, and guarantees to traverse elements as
	 * they existed upon construction of the iterator, and may (but is not
	 * guaranteed to) reflect any modifications subsequent to construction.
	 *
	 * @return an iterator over the elements in this queue in proper sequence
	 */
	public Iterator<E> iterator() {
		return new Itr();
	}

	private class Itr implements Iterator<E> {
		/*
		 * Basic weakly-consistent iterator. At all times hold the next item to
		 * hand out so that if hasNext() reports true, we will still have it to
		 * return even if lost race with a take etc.
		 */
		private Node<E> current;
		private Node<E> lastRet;
		private E currentElement;

		Itr() {
			lockAll();
			try {
				current = head.next;
				if (current != null)
					currentElement = current.item;
			} finally {
				unlockAll();
			}
		}

		public boolean hasNext() {
			return current != null;
		}

		/**
		 * Returns the next live successor of p, or null if no such.
		 *
		 * Unlike other traversal methods, iterators need to handle both: -
		 * dequeued nodes (p.next == p) - (possibly multiple) interior removed
		 * nodes (p.item == null)
		 */
		private Node<E> nextNode(Node<E> p) {
			for (;;) {
				Node<E> s = p.next;
				if (s == p)
					return head.next;
				if (s == null || s.item != null)
					return s;
				p = s;
			}
		}

		public E next() {
			lockAll();
			try {
				if (current == null)
					throw new NoSuchElementException();
				E x = currentElement;
				lastRet = current;
				current = nextNode(current);
				currentElement = (current == null) ? null : current.item;
				return x;
			} finally {
				unlockAll();
			}
		}

		public void remove() {
			if (lastRet == null)
				throw new IllegalStateException();
			lockAll();
			try {
				Node<E> node = lastRet;
				lastRet = null;
				for (Node<E> trail = head, p = trail.next; p != null; trail = p, p = p.next) {
					if (p == node) {
						unlink(p, trail);
						break;
					}
				}
			} finally {
				unlockAll();
			}
		}
	}

	/**
	 * Save the state to a stream (that is, serialize it).
	 *
	 * @serialData The capacity is emitted (int), followed by all of its
	 *             elements (each an {@code Object}) in the proper order,
	 *             followed by a null
	 * @param s
	 *            the stream
	 */
	private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {

		lockAll();
		try {
			// Write out any hidden stuff, plus capacity
			s.defaultWriteObject();

			// Write out all elements in the proper order.
			for (Node<E> p = head.next; p != null; p = p.next)
				s.writeObject(p.item);

			// Use trailing null as sentinel
			s.writeObject(null);
		} finally {
			unlockAll();
		}
	}

	/**
	 * Reconstitute this queue instance from a stream (that is, deserialize it).
	 *
	 * @param s
	 *            the stream
	 */
	private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
		// Read in capacity, and any hidden stuff
		s.defaultReadObject();

		count.set(0);
		last = head = new Node<E>(null);

		// Read in all elements and place in queue
		for (;;) {
			@SuppressWarnings("unchecked")
			E item = (E) s.readObject();
			if (item == null)
				break;
			add(item);
		}
	}
}
